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Date:      Sat, 28 May 2022 15:30:18 +0000
From:      Rick Macklem <rmacklem@uoguelph.ca>
To:        Kurt Jaeger <pi@freebsd.org>
Cc:        "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org>
Subject:   Re: FreeBSD 12.3/13.1 NFS client hang
Message-ID:  <YQBPR0101MB9742B91118878E58691DB94CDDDB9@YQBPR0101MB9742.CANPRD01.PROD.OUTLOOK.COM>
In-Reply-To: <YpHZb0fgsmbBrxD8@fc.opsec.eu>
References:  <YpEwxdGCouUUFHiE@shipon.lysator.liu.se> <YQBPR0101MB9742280313FC17543132A61CDDD89@YQBPR0101MB9742.CANPRD01.PROD.OUTLOOK.COM> <YpHZb0fgsmbBrxD8@fc.opsec.eu>

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Kurt Jaeger <pi@freebsd.org> wrote:=0A=
> > > I'm having issues with the NFS clients on FreeBSD 12.3 and 13.1=0A=
>=0A=
> I have it with an 13.0p7 client against an 13.1 server with=0A=
> a hanging soft-mount (I tried unmount to change it to a hard mount).=0A=
> =0A=
> 61585  93- D+        0:00.00 umount /office/serv=0A=
> 61635 133  D         0:00.00 umount -f /office/serv=0A=
> 7784 138  D         0:00.00 umount -N /office/serv=0A=
The first umount must be "-N". Once you've hung a non "-N" umount,=0A=
rebooting is the only option.=0A=
(I have thought of doing a "umount -N -A" (for all NFS mounts), which=0A=
would allow it to kill off all NFS activity without even finding the pathna=
me=0A=
for the mountpoint, but I have not done so.)=0A=
=0A=
> and procstat:=0A=
>=0A=
> # procstat -kk 7784=0A=
>  PID    TID COMM                TDNAME              KSTACK=0A=
> 7784 107226 umount              -                   mi_switch+0xc1 sleepl=
k+0xec lockmgr_xlock_hard+0x345 _vn_lock+0x48 vget_finish+0x21 cache_lookup=
+0x299 vfs_cache_lookup+0x7b lookup+0x68c namei+0x487 kern_unmount+0x164 am=
d64_syscall+0x10c fast_syscall_common+0xf8=0A=
> # procstat -kk 61635=0A=
>  PID    TID COMM                TDNAME              KSTACK=0A=
> 61635 775458 umount              -                   mi_switch+0xc1 sleep=
lk+0xec lockmgr_slock_hard+0x382 _vn_lock+0x48 vget_finish+0x21 cache_looku=
p+0x299 vfs_cache_lookup+0x7b lookup+0x68c namei+0x487 sys_statfs+0xc3 amd6=
4_syscall+0x10c fast_syscall_common+0xf8=0A=
> # procstat -kk 61585=0A=
>  PID    TID COMM                TDNAME              KSTACK=0A=
> 61585 516164 umount              -                   mi_switch+0xc1 sleep=
lk+0xec lockmgr_xlock_hard+0x345 nfs_lock+0x2c vop_sigdefer+0x2b _vn_lock+0=
x48 vflush+0x151 nfs_unmount+0xc3 vfs_unmount_sigdefer+0x2e dounmount+0x437=
 kern_unmount+0x332 amd64_syscall+0x10c fast_syscall_common+0xf8=0A=
These just show that they are waiting for NFS vnodes. In the "ps" there are=
=0A=
threads waiting on zfs vnodes as well.=0A=
=0A=
> ps-axHl can be found at=0A=
> =0A=
> https://people.freebsd.org/~pi/logs/ps-axHl.txt=0A=
I suspect your problem might be related to wired pages. Note that=0A=
several threads are sleeping on "vmopar". I'm no vm guy, but I=0A=
think that might mean too many pages have become wired.=0A=
=0A=
rick=0A=
=0A=
> > systems hanging when using a CentOS 7 server.=0A=
> First, make sure you are using hard mounts. "soft" or "intr" mounts won't=
=0A=
> work and will mess up the session sooner or later. (A messed up session c=
ould=0A=
> result in no free slots on the session and that will wedge threads in=0A=
> nfsv4_sequencelookup() as you describe.=0A=
> (This is briefly described in the BUGS section of "man mount_nfs".)=0A=
>=0A=
> Do a:=0A=
> # nfsstat -m=0A=
> on the clients and look for "hard".=0A=
=0A=
No output at all for that 8-(=0A=
=0A=
--=0A=
pi@FreeBSD.org         +49 171 3101372                  Now what ?=0A=
=0A=



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